GSR Flashcards
What is the stain classification of Gordon and Sweet’s Reticulin (GSR)?
Connective tissue stain
What is the target tissue component of GSR?
Reticulin fibers
What is the mechanism of staining of GSR?
Metallic impregnation
What is the principle of staining of GSR?
Argyrophil metallic impregnation and metallic substitution
What are the positive controls that can be used for GSR?
Liver, spleen, lymph node, and adrenal gland
What tissue component is produced by fibroblasts as tropocollagen?
Reticulin fibers
What is the collagen classification of reticulin fibers?
Types 3 and 4 collagen
What is the composition of reticulin fibers?
Carbohydrate coating (glycoprotein + polysaccharide-containing proteoglycans)
Where are reticulin fibers distributed?
Basement membrane, meshwork support of hemopoietic tissues, and pre-collagenous reticulin in the dermis
Is reticulin elastic?
No
Does reticulin have tensile strength?
No
Are reticulin fibers birefringent?
Only weakly
What are the 8 steps of GSR?
- Oxidation with acidified KMnO4
- Bleaching with oxalic acid
- Sensitization with ferric ammonium sulphate
- Silver impregnation with ammoniacal silver solution
- Reduction with 10% formalin
- Toning with gold chloride
- Fixation with sodium thiosulphate
- Counterstain with nuclear fast red
What happens chemically during the oxidation step of GSR?
Adjacent glycol groups of the hexose sugars are oxidized to aldehydes
Why do we need the oxidation step in GSR?
It’s required for the impregnation of the reticulin fibers
What does acidified KMnO4 do during the oxidation step of GSR?
KMnO4 produces reactive aldehyde groups (these react indirectly with silver)
H2SO4 suppresses impregnation of the nuclei
What happens in the bleaching step of GSR?
Removal of the undesired effects of the oxidizing agent
What does oxalic acid do in the bleaching step of GSR?
Removes KMnO4 discoloration
Why do we need to use iron for sensitization in GSR?
Iron is more reactive than silver, we need a more reactive metal for the silver impregnation to work
Which step in GSR is the metallic impregnation step?
Sensitization
What kind of chemical compound is required for sensitization in GSR? Why?
a metallic salt. It reacts with aldehyde groups on the reticulin and forms complexes to allow for the sliver impregnation to work.
What is the definition of impregnation in GSR?
The deposition of metallic salts, ON or AROUND but NOT IN, the tissue component to be demonstrated
In what step of GSR does metallic substitution happen?
Silver impregnation step
What does the tissue get treated with in the silver impregnation step of GSR?
An ammoniacal or diamine silver complex
What problem do we run into in the silver impregnation step of GSR?
There’s not enough silver deposits to provide adequate visibility
What do the aldehyde groups do to the diamine silver in the silver impregnation step of GSR?
They reduce it to metallic silver
